Broad band antenna



May 23," 1950 D. W. WILSON El AL BROAD BAND ANTENNA Filed Oct. 16, 1945 DOUGLAS" w. WILSON RALPH E. TAYLOR GENER ATOR mmo FREQUENCY line H.

Patented May 23, 1950 tidbits BROAD BAND ANQENNA Dauz eewilson a diltalnhilii eller, eshmmn- 1.

Application October; 1945, SeriatNo. 622,660

(01.. 2599433). (Granted under helact o ;..Mam 3..183 as :Qlairns.

amended April 30. eeaiielzii 15;

This invention relates to wide-band antennas.

An object of the inventionis to provide an antenna, which terminates a transmission line inan impedance producing a small reflection over a wide frequency band.

Another object of the invention is to provide a novel antenna operating ,efii ciently over a wide frequency band. e

4 other bie ts ea u es. neadye sss 9 th invention will be apparent from he following dese p ion an t a c mp n in awin w m: V

F g. ;1 isa top new prim y-em odimea o an a enn in ste s h-th in: ra it s. and. v

e- 2 i .aerqs secti nalr ew o heembqd 1.1. 11 s own. n g. tak n in the'plane 2:1-v

Re e r ne pqwtolthe draw ntennai accordance with the invention comprises a conical element to, a section M of coaxial transmission line extending coaxially through the apex of the conical element In, an extension l5 of the inner conductor of the transmission line beyond the end of the line section l4, and a plurality of electrically conductive rods l2, l3. The conical element I0 is constructed of electrically conductive material. The rods l2, l3 are also made of conductive material and may be of tubular or solid cross-section. The conical element I0 is conductively attached near its apex to the line section id in the plane of its intersection therewith. The rods l2, l3 preferably are positioned perpendicular to each other and to the line section M in order to minimize undesirable electrical coupling between each rod and the other components Of the antenna.

In addition, insulators (not shown) may be incorporated in the antenna in order to provide adequate rigidity and strength without affecting appreciably the electrical characteristic of the antenna.

As shown in the drawing, the antenna may be energized by a radio frequency generator l6 coupled to the antenna by means of the transmission a In order to efiect efiicient radiation of the power developed by the generator l6, it is necessary that the characteristic impedance of the line H match the antenna impedance measured at the lower end of the line section M. A further requirement for the eflicient radiation of energy is the elimination of radio frequency current on the exterior surface of the line I l.

The rods l2 and I3 terminate the outer surface of line section It near the apex of the conical .2 agen y -chaneed- I ievar ati n of. h admit tans: s q t e tends torompeesatefo the Le new: me it am.Lise-tha l a i we t -1 .1 8 I I wi h at e se. ably ons ant im ed nce as th f equenc raried- Iherodsw. 1. m yhe-qqe r eted otha he. lens m hereof maype d d ex mp e. te sqepins. t pe .9 be used.

The sur a est ,theant eaa com n tadiate th nergysu plie to the a enna by the.

-' order of 125 ohms.

element It in admittances which vary as the fre- 5;

enter it- The lin s amen nsiqtmer which ma ch s the ee tmailr 'eh-b itt aeenaply cpnsta t IQ$JP$RQ che ae eltistieslime arran ement: the 1 tai gat the t l flllettqrifi qj, anc 01". thee ii e lllandlat he same tim suppresses y eape l a tion'the normally varying reactance characteristic of the radiating portion of the antenna.

The conical element It! constitutes a broad band detuning device which preserves the unbalanced property of the coaxial transmission line I I and thereby prevents radiation from the outer surface of the line H.

The dimensions of an antenna according to the invention may be referred to the wavelength, A, corresponding to the lower frequency limit of the band of frequencies over which eflicient operation is desired. The dimensions indicated in the drawing are those of a model of the invention which proved to operate satisfactorily over a. two to one frequency ratio. In the particular embodiment herein illustrated the extended portions of conductor l4 and inner conductor I5 are each .11 A long. Rods l2 and I3 are .11 A and .15 A long respectively and conical member I0 .13 A long.

In a satisfactory model of the antenna, which was designed to match a 50 chm transmission line, the optimum value of characteristic impedance of the line section M was found to be of the The optimum lengths of the rodsl2, I3 may best be determined experimentally by adjusting the lengths of the rods individually to maintain a satisfactory impedance match between the line ll and the antenna over the entire operating frequency band.

It will be understood that the invention is not limited by the exemplary embodiment herein described and that the scope of the invention is to be determined by reference to the appended claims.

The invention described herein may be manufacti-ired and used by or for the Government of the United States oi America for governmental purposes without the payment of any royalties thereon or therefor.

What is claimed is:

1. An antenna comprising a substantially conical element, a coaxial transmission line passing through the conical element coaxially therewith, the outer conductor of the line being conductive ly attached to the conical element in the plane 01, intersection therebetween, an extension of the outer conductor of the line beyond the plane at intersection with the conical element, said ex: tension consisting of a cylindrical conductor equal to a fractional part of a quarter wave length long at the low end of the frequency band to be covered and an extension of similarlength of the inner conductor of the line beyond-the'endof the outer conductor. V 2. An antenna comprising asubstantially con-' ical element, a coaxial transmission line passing through the conical element coaxially therewith, the outer conductor of the'line being conductively attached to the conicalelement in-theplane of intersection therebetween, an extension of the outer conductor of the line beyond the apex of the conical element, an extension of the inner conductor of the line beyond the end of the outer conductor, and a plurality of conductive rods conductively attached to the outer'condu'ctor and extending perpendicularly away therefrom in said plane of intersection.

1 3; An antenna comprising a substantially conical element, a coaxial transmission line passing through the conical element coaxialy therewith, the outer conductor of the line being conductively attached to the conical element in the plane'ol intersection therebetween, an extension of the outer conductor of the'line beyond the apexoi the conical element," an' extension of the inner conductor of the line beyond the end of the outer conductor, and a plurality of conductive rods of unequal lengths conductively attached to the out er conductor and extending perpendicularly away 5 therefrom in said plane of intersection.

4. An antenna comp ising. a substantially con ical element, a coaxial transmission line passing through the conical element'co'axially therewith, the outer conductor of said line being conductive- "1'0"ly attached to the conical element in the plane of intersection therebetween, an extension of the outer conductor of said line beyond the apex of the conical element, an extension of the inner conductor of said line beyond the end of the outer 35 cond uctor, and a conducting surface extending at right angles to" the outer conductor of said transmission line and attached thereto at the ,plane of intersection of said line and said conidal element.

DOUGLAS W. WILSON.

I RALPH E. TAYLOR.

REFERENCES CITED 'The following references are of record in the g5 file 'of this patent: f

0 V UNITED STATES. PATENTS Number- Name Date 2,026,652 Ponte Jan. 7, 1936 30 "2,110,159 Landon Mar. 8, 1938 2,175,252 Carter 2. a--- -'Oct.' 10, 1939" "2,184,729 Bailey" Dec.-26, 1939 2,218,741 Buschbeck Oct. 22, 1940 2,239,724 -Lindenb1ad' Apr. 29, 1941 35 2,274,389 -Von Baeyer Feb. 24, 1942 2,368,663 Kandoian Feb. 6, 1945' 2,370,053 Lindenblad Feb. 20, 1945 2,411,976 Dec. 3, 1946 

